Do I Have the Wrong Cartridge?

I recently got back into playing vinyl on my Linn Axis (fully serviced), but needed a new cart. Since 80% of my listening is on an ARC CD3 and not knowing how often I’ll use the TT, I set a budget of only $300 on a MM and went to my local HiFi shop. They recommended a Rega Elys II.

Now to my problem...I listen to classical music and it sounds awful with this cart; strings and brass are harsh and music sounds thin overall. All my LPs are top class, pressed in Germany and Holland.
To test my TT, I played some Rock albums and they all sounded excellent; great dynamics, wide soundstaging. Records played were a wide variety; Led Zeppelin, Jeff Beck, Mahavishnu Orch, Kraftwerk.

So I ask you, can a middle of the road cartridge like this Rega only sound good on a particular style of music? I was told this Rega was a good all-around cart and BTW, it’s non-returnable.

Looking for any explanation and advice.
Many thanks.